XCell Spectra-G Model – Additional Operators Guide
Page 14 of 16
Copyright
12/5/2004
Miniature Aircraft USA
4.4.4. Full Power Settings
Obviously the only way to determine if the full power setting is correct is to operate the
helicopter at full power. If you are unable or uncomfortable with doing this, either get
someone who can to operate the model, or simply rely on the normal settings indicated
earlier (the will be close enough).
To begin with, full throttle/full pitch operation is no different with a gasoline motor as with any
other power source. Too much pitch can cause the engine to bog and overheat regardless of
fuel mixture. So if the engine bogs significantly at full collective, the first thing to check is the
pitch setting. Although this will be dependent on blade length, cord, profile and weight, the
engine should be capable of operating at full power with 10 degrees of positive or negative
pitch when using blades shorter than 725mm.
If mixture adjustments are needed, the high-speed needle is a “fine” adjustment, so changes
to the needle itself are less critical.
An overly rich high-speed needle will result in causing the engine to 4-stroke at full power and
an overly lean setting will result in excess vibration, overheating the engine and perhaps
seizing it. Neither situation will result in optimum power.
Until you become comfortable with the right “sound” of the model when the mixture is correct,
follow this procedure to check the mixture. Operate the model at full power for about 5
minutes, then land, allow the engine too cool and examine the spark plug (see earlier
observations). Adjust the high-speed needle accordingly.
4.5. Stopping the Motor
To stop the motor in the model, either use the throttle position by closing the throttle fully or if
you are holding the model and the air cleaner assembly you are using includes a choke,
simply close it.
4.6. Engine/Muffler Heat
Be careful!! The motor and the exhaust get VERY hot and will remain hot for longer than you
might think. Be careful not to get any flammable material on them when they are hot.
4.7. Cooling The Engine
When initially shut down, the temperature of these motors will increase by as much as 75
degrees and then gradually start to cool off. Sometime referred to as “heat soak”, this is
simply a normal condition.
It is suggested that if possible, let the motor idle for a couple of minutes before shutting it
down, especially if the model has been flown hard. By idling the motor just for a minute, it will
cool down significantly and there will be less heat soak.
